The first three chapters of C # That we have learned in those years,

The first three chapters of C # That we have learned in those years,

Chapter 1

1. main method of c #

The return value can be void or int.

Four Main () methods:

Static void Main (){}

 

Static void Main () {string [] args}

 

Static int Main (){}

 

Static int Main () {string [] args}

2. C # VARIABLES

Common Data Types in c #: integer int, float, and string Boolean bool

Naming rules for variables in c:

1, composition: English letters, numbers, "_"

2, start with: English letter, "_"

3. Keywords cannot be used;

 

3. constants and variables in C #

Variable: variable amount

For example:

Int num = 5;

Num = 7;

 

Constant: Once defined, its value cannot be modified in subsequent code.

For example:

Int num = 5;

 

4. Massive code folding

The shortcut key is Ctrl + K + S.

Const data type constant name = value;

Note: constants cannot be re-assigned.

Constants must be initialized during declaration.

Constant naming rules: 01, meaningful 02, both large write 03, length should be long

 

5. Input and Output

Output to the console:

Console. WriteLine () method -- line feed after output

Console. WriteLine

For example: Console. WriteLine ("My course name is: {0}", course );

{0} is a placeholder

Use {0}, {1}, and {2} in turn to correspond to the variables in the Variable list

 

Read from the console:

Console. ReadLine ();

 

6. Access Modifier

Access modifiers: such as public and private

Return type: such as int, double, string, void, etc.

 

Comments in 7. c #

Single line comment ://

Multi-line comment :/**/

Document Note :/**

*/

Chapter 2

1. c #AndJavaOfSwitchWhat are the differences in statement usage?

01. in java, the expression value after switch can only be (int/char), but the value in c # Can Be (int/char/string)

02. There can be no break statement after case in java, but not in c #.

 

2.IfCondition Structure

C # is exactly the same as java

 

3. Array

Int [] num = new int [5] {0, 1, 2, 3, 4 };

Int [] num = new int [] {0, 1, 2, 3, 4}; omitted Length

Int [] num = {0, 1, 2, 3, 4}; omitting new

In C #, the length of an array can be omitted, while that of new.

Elements in the loop output Array

For (int I = 0; I <array. Length; I ++) // output all elements in the array

{

Console. WriteLine (array [I]);

}

4. Use foreach to traverse array elements cyclically

A foreach loop is generally used to traverse the entire array.

Syntax: foreach (element type variable name in set or array name)

{

// Statement

}

5. Double Loop

Int I, j; // cyclic variable

For (I = 1; I <= 5; I ++)

{

// The number of numbers printed per line is controlled cyclically in the inner layer

For (j = 1; j <= I; j ++)

{

Console. Write (j );

}

Console. WriteLine ();

}

 

6.Bubble Sorting

Rule: compare two adjacent numbers each time, small switches to the front, and the maximum number after each wheel speed switches to the maximum